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St170 Conrod Lengths - Cylinder No. 1


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I am a newbie, so be gentle !

Just bought an 2003, Mk1 Focus ST170 silvertop engine for a complete overhaul and rebuild (115,000 on the clock), to go into my kitcar.

Spent a very happy weekend stripping it down and all looks to be in good shape.... however, I have just removed the pistons and conrods and noticed that cylinder no. 1 has a slightly curved conrod, which is approx 2.5mm shorter than the other 3.

I noticed that at TDC, cylinder no. 1 did not rise as far as no. 4, and the shorter curved conrod would certainly explain that.

Can anyone explain what this is all about, why is it curved and shorter than the others ?

.... OR have I got a very dodgy conrod ???


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Thanks Stef,

I have to say I have never come across a curved conrod before, it is quite like a banana !!

Engine must have been vibrating like a good 'un and compression / power down in No.1.

Oh well, new conrod by the looks of it then.

Any recommendations where to source one ?

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The engine may have dropped a valve which bent the conrod and have had the head rebuilt or, more likely, replaced, or it could have been hydralocked due to driving through floods or oil or fuel in the cylinder

I would give the head a good check over, and the crank, including the big end of the cylinder with the bent conrod

Nows your chance to get a set of Carrillo rods and get the engine rebuilt/ blueprinted by a top tuner!

A cheaper alternative would be to ask round (all) the (Ford) forums, someone may have rod/s lying around

You should post up a pic of the bent rod!

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Thanks for all the possibilities - the head is immaculate, no signs of any damage or repairs. Top of piston also clean as a whistle so (unless changed) no obvious damage. So I don't think a dropped valve.

I attach a photo of the bend rod next to a straight one ! See if you can spot the difference :)



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When you said about 2.5mm shorter i didn't really think much of how bent the conrod would be but now that I see it like that!

Only thing that really jumps into my head now is it possible that its drawn in water on no.1 cylinder?

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